Yes, there is!
You'll have to use zmmailbox for this. It would be something like:
To explain this a bit. You're creating a mountpoint (cm) called mount_name for email@example.com with an appointment type view which comes from firstname.lastname@example.org's /shared_cal_name . You should run this as zimbra user preferably on your mailstore server (I think). Hope that makes sense
zmmailbox -z -m email@example.com cm -V appointment /shared_cal_name firstname.lastname@example.org mount_name
Further reading: Zmmailbox - Zimbra :: Wiki